A new version 2.0b is available, which includes 3D models/ray tracing, station elevation, and an improved weighting scheme. If you would like to use/test this beta version, please email me at felixw@ldeo.columbia.edu.

HypoDD is a computer program that implements the double-difference earthquake location algorithm of Waldhauser & Ellsworth (2000). The program package includes source codes, user guide (Waldhauser, 2001), and several example data sets and is freely available from this site and via anonymous ftp. The file below, BugList_1.3, lists errors found in the current version (HypoDD_1.3) and tells you how to fix them. Thanks to those who pointed them out.